In a conventional balustrade device for an escalator, a plurality of outer decks are arranged in line with a direction of travel of steps and abut against each other at the positions of balustrade posts. Each balustrade post passes through a notch provided in the outer decks. The longitudinal-direction dimension of the outer decks allows a margin with respect the dimension of the balustrade posts in the same direction. Covers which close the gaps between the balustrade posts and the outer decks are provided on top of the outer decks (see PTL 1, for example).